PATERSON — A developer who owns more than 300 apartment buildings in some of Paterson’s most crime-ridden neighborhoods deployed armed security guards on Thursday to patrol three of his properties.

The developer, Charles Florio, hired an Essex County company, Global Mark, which he said uses retired Newark police officers. Florio said two guards on Thursday patrolled the buildings he owns on Auburn Street, in a drug-infested area where Paterson police say they have made more than 200 narcotics arrests in the past three years. Two teenagers were shot — one of them fatally — earlier this month in an apartment next to a building owned by Florio.

The developer said the security guards on Thursday chased about five squatters from a vacant apartment at 83 Auburn St. “These guys are not playing around,” said Florio. “We’re not talking about mall security guards.”

Paterson Police Director Jerry Speziale said private security companies with requisite licenses and bonding are allowed to deploy armed guards. Speziale said he learned of Florio’s decision through media inquiries and expressed concern that undercover Paterson police officers could be placed in jeopardy if the armed guards mistake them for criminals.

On Thursday afternoon, two of the guards sat in a company car in front of 87 Auburn St. Down the block was a Paterson police patrol car with an officer inside. Around the corner, on Fair Street, was another city police vehicle. The usual bustle of illicit activity was gone from Auburn Street at 2 p.m.

James Dawson, who had lived in the building where the killing took place, said he has noticed a decline in violence and drug dealing in the area in the past two weeks. “I say they needed security, there were a lot of shootings,” said Dawson, who said he has been moving around to various relatives’ homes and sometimes sleeping in hallways after his home was condemned.

After city officials shut down the six-unit building where the homicide took place, Florio criticized Paterson, saying the city ought to crack down on drug dealers instead of landlords. At the time, he said he would hire a private security company as well as install surveillance cameras and extra lighting near his worst properties.

Florio said the security guards would start by spending 10 hours a day on Auburn, seven days a week. At first, he said, they would be deployed mainly in the daytime, while his construction crews did work on 83 Auburn. After that, he said, the hours would vary. Florio also owns 42 and 50 Auburn St., about a block from the other property.

If the private security works on Auburn, Florio said, he would expand the effort to other problem-plagued Paterson properties he owns, including locations on North Main and East Main streets. Florio said he is spending about $7,500 a week on the security.

“That just shows I’m not just looking to make a profit,” said Florio. “I’m looking to make the neighborhood better.”